Optical communication techniques transmit data using signals such as infrared light, visible light, ultraviolet light, and other optical carrier signals, and are used in high-speed networks as well as in interfaces between components of a single system. In some of these techniques, transmitted data may be encoded by modulating an attribute of the carrier signal using an optical modulator. One particular class of optical modulator includes ring modulators.
A ring modulator may have a linear waveguide in close proximity to a substantially circular resonator, another type of waveguide. When an optical carrier signal is applied to the linear waveguide, optical coupling may cause a portion of the signal to be transferred to the resonator. Optical coupling may also cause the optical signal in the resonator to be transferred back to the linear waveguide. Thus, the output at the far end of the linear waveguide may depend on the interference between the portion of the carrier signal that flows straight through the linear waveguide and the portion that is diverted into and back out of the resonator. To encode a data signal, the ring modulator may include a mechanism that affects the behavior of the signal portion in the resonator, which affects how it interferes with the signal portion that remains in the linear waveguide. In turn, this affects the amplitude of the output signal.